JPH09135069A - Surface mounting multilayer substrate and liquid crystal display device utilizing the same substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mount a variety of surface mounting electronic parts including a BGA type with the high reliability and at low cost using solder. SOLUTION: A surface mounting multilayer substrate 1 having mounted a plurality of electronic parts including a ball grid array type electronic part 2a has resist film 1a at the external circumference surface of each soldering pad 3a located at the mounting position of at least the ball grid array type electronic part 2 and the film thickness of this resist film 1a is set almost equal to the gap between the external circumference surface after the mounting of the ball grid array type electronic part 2a and the surface mounting substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly accurate surface mount multilayer substrate which is highly accurate and eliminates defective soldering, and a liquid crystal display device using this substrate.

[0002]

2. Description of the Related Art Liquid crystal display devices, video cameras, and other electronic devices have a strong need for smaller size and lighter weight, and accordingly, small electronic parts such as semiconductor parts forming signal circuits and drive control circuits thereof are becoming smaller. In addition, it is necessary to increase the density of wiring patterns on circuit boards (hereinafter, also simply referred to as boards) on which these electronic components are mounted and to reduce costs.

The electronic component mounted on the circuit board is a surface mount type called a flat package, and a so-called surface mount multilayer board having wiring patterns formed in a plurality of layers is widely used as a circuit board for mounting the electronic package. A method of directly soldering the terminals (lead pins or ball grids) of these flat packages to the wiring pattern of the surface mount multilayer substrate is often used.

FIG. 9 is a schematic view for explaining an example of a conventional surface-mount multilayer substrate. (A) is a plan view, (b) is a side view, and (c) is a structure of part A of (b). It is a partial sectional view explaining.

In the figure, reference numeral 1 is a surface-mounted multilayer substrate, 1c.
Are alignment marks, 2 are mounted parts, 2a are BGA type parts, 2b are SOP type parts, 2c are SOJ type parts, 2ar
Is a solder ball, 3 is a wiring pattern, and 3a is a soldering pad (hereinafter, simply referred to as a pad).

The surface-mount multi-layer substrate 1 is formed by laminating a plurality of wiring patterns, and in general, terminals (pads) formed on the wiring pattern on the surface of the surface are mounted with lead parts or ball grids (hereinafter also referred to as solder balls). I say) and solder it.

In the SOP type component 2b and the SOJ type component 2c, the lead pins formed on the side edges of the flat package are soldered in accordance with the wiring pattern of the circuit board. As the number of ball grids increases, a large number of ball grids made of solder balls are formed on the back surface of a flat package, and the array of the ball grids is soldered to the pads formed on the wiring pattern of the board. The array type part 2a tends to be adopted often.

As shown in (a) and (b) of FIG.
The shape component 2b and the SOJ type component 2c are soldered with their lead pins exposed on the surface of the circuit board.
The solder ball formed on the back surface of the component A is invisible because it is shielded by the flat package.

That is, FIG. 1C shows the soldered B
It is a partial sectional view of (b) which expands and shows the A section of a GA component, and the spherical solder (solder ball) 2ar added to the element terminal of the said BGA component 2a is attached to the back surface of the BGA component 2a.
It is mounted by soldering to the pads 3a of the multilayer wiring pattern 3 formed on. It should be noted that in the figure, before soldering, a spherical solder flows due to soldering due to heating, becomes an indeterminate shape, and is fixed to the pad 3a.

FIG. 10 is an explanatory view of a schematic structure of various surface mount type flat packages. (A-1) is a rear view of the SOP type, (a-2) is a side view of (a-1), (B-
1) is a rear view of SOJ type, (b-2) is a side view of (b-1), (c-1) is a rear view of BGA type, (c-2) is a side view of (c-1). Is.

(A-1) (a-2) and (b-1) (b-
As shown in 2), the SOP type and SOJ type flat packages 2b, 2c are provided with lead pins 2br, 2cr on the side surface of the package body.
2cr is soldered to the wiring pattern of the circuit board,
As shown in (c-1) and (c-2), the BGA type package has a ball grid 2ar made of spherical solder (solder ball) on its back surface.

FIG. 11 is an explanatory view of a dimension example of a BGA type electronic component, (a) is a top view, (b) is a rear view, and (c).
Is a side view, and (d) is an enlarged cross-sectional view for explaining the structure of the B portion of (c).

As shown in (a), (b) and (c) of FIG.
This BGA type electronic component (BGA type flat package)
The main body of 2a has a rectangular shape with one side of 26.8 mm, the thickness is 1.46 mm, the diameter of the ball grid formed on the back surface of the main body is 0.90 mm, and the ball grid interval is 1.5.
The height of the ball grid from the back of the main body is 0 mm.
70 mm.

The portion of the ball grid 2ar is, as shown in FIG. 1D, a main body wiring pattern formed of copper, nickel, or Au for connecting to a copper element terminal formed inside the main body. The solder balls 2ar are connected to the solder balls 5, and the solder balls 2ar are insulated by the resist 6. The size and spacing of the solder balls are determined by the content of the electronic components.

FIG. 12 is an explanatory view of a conventional soldering work of a flat package type electronic component to a surface mounting multilayer substrate.

In FIG. 1, first, in step 1, paste solder 7 is applied to the surface of the soldering wiring pattern (pad 3a) of the surface mount multilayer substrate 1 by a printing method.

However, in the BGA type electronic component, the paste solder 7 may not be applied as shown in B.

Next, in step 2, the electronic component 2 is mounted on the paste solder 7 (or the wiring pattern pad 3a in the case of the above B) applied on the wiring pattern pad 3a.

Then, in step 3, the solder paste 7 and the solder balls 2ar or the solder balls 2ar are melted and soldered by heat treatment.

Through such an operation, a surface-mounting multilayer board having electronic components mounted thereon can be obtained.

[0021]

FIG. 13 is a sectional view of a soldering portion for explaining a mounting structure of an electronic component in a conventional surface-mounting multilayer board, and FIG. 13 (a) shows a wiring pattern formed on the board. A principal part cross-sectional view when the resist film is not applied to portions other than the soldered part, (b) is a main part cross-sectional view when the resist film is applied to portions other than the soldered part of the wiring pattern formed on the substrate, and (c) is 3A and 3B are a plan view and a sectional view of a main part of a wiring pattern and a pad portion thereof in FIGS.

In FIG. 1A, the ball grid 2ar is melted by placing and heating the ball grid 2ar of the BGA type electronic component 2a on the pad 3a of the wiring pattern formed on the wiring board 1. 'Indicates that soldering has been performed, and 2a' indicates BGA before soldering.
Shows the mounting position of the electronic component.

However, with the densification of the wiring pattern, that is, the densification of the solder balls 2ar of the above electronic parts,
The gap between the pads 3a may become narrow, and a short circuit between adjacent pads may occur as shown in FIGS.

Further, as shown in FIG.
Even if the resist film 1a for insulation is applied to the surface of the above and the outer periphery of the pad 3a of the wiring pattern, the short circuit as shown in E may still occur.

As shown in FIG. 3C, the above (a)
In (b), the wiring pattern 3 having a diameter of 0.4 mm and wired to the multilayer substrate 1 has a thickness of 0.05 mm and a diameter of 1.0 mm.
Pads 3a are arranged at a pitch of 1.50 mm, in the case of the above (a), the BGA type electronic component 2a is soldered thereon, and in the above (b), the resist film 1a is formed around the pad 3a. It is applied in a thickness of 02 mm.

In the method (a), the work time can be saved by not requiring the step of coating the resist film, but the short circuit between the adjacent pads is conspicuous, and the method (b) requires the resist coating operation. In short, the frequency of occurrence of short circuits is reduced, which is an excellent means for improving quality. But,
Even if a resist film is applied, it is not possible to eliminate the occurrence of short circuits as described above.

FIG. 14 is a cross-sectional view of the principal part for explaining the structure of the soldering part when an insulating resist film is applied and a BGA type electronic component having a solder ball pitch of 1.5 mm is soldered under ideal conditions. In the figure, (a) shows a state before solder heating, and (b) shows a state in which soldering is completed by heating.

In the figure, the BGA electronic component 2 to be mounted is installed.
Solder balls 2 forming a ball grid in which a is formed
The diameter of ar is 0.9 mm and its pitch is 1.50 mm.
Then, the height from the back surface of the electronic component is 0.7 mm.

Further, the pad 3a of the wiring pattern 3 formed on the multilayer substrate 1 has a diameter of 1.0 mm formed by nickel plating and gold plating finish, as shown in FIG.
It is formed to a thickness of 0.01 mm. The resist film 1a having a thickness of 0.02 mm is formed on the outer peripheral surface of the pad.
The pad surrounded by is applied so that the diameter of the pad is 0.8 mm.

When the BGA type electronic component 2a is mounted on the substrate 1, the ball grid of the electronic component 2a, that is, the center line of the solder ball 2ar is positioned and heated so as to coincide with the center line of the pad 3a.

In (b), which shows a cross section of the main part in a state of being soldered by heating, the solder ball 2ar is melted and spreads on the pad 3a and is fixed at a height of about 0.35 mm as indicated by 2ar '. .

Under ideal conditions, the distance F between adjacent melted and fixed solders is about 0.3 mm, and sufficient insulation is secured.

FIG. 15 is a cross-sectional view of the principal part for explaining the structure of the soldering portion when an insulating resist film is applied and a BGA type electronic component having a solder ball pitch of 1.0 mm is soldered under ideal conditions. In the figure, (a) shows a state before solder heating, and (b) shows a state in which soldering is completed by heating.

In FIG. 1A, a wiring pattern 3 having a diameter of 0.4 mm formed on the substrate 1 is nickel-plated and gold-plated to form a pad 3a having a diameter of 0.8 mm and a thickness of 0.01 mm. A resist film 1a having a thickness of 0.02 mm is applied to the outer peripheral surface to secure a soldering surface having a diameter of 0.6 mm.

The solder ball 2ar has a height of 0.46 mm from the back surface of the BGA electronic component 2a to be mounted and a diameter of 0.5.
It is formed in mm.

When the BGA type electronic component 2a is mounted on the substrate 1, the ball grid of the electronic component 2a, that is, the center line of the solder ball 2ar is positioned so as to coincide with the center line of the pad 3a. The BGA electronic component in this state is indicated by 2a '.

FIG. 3B shows a cross section of a main part in a state where soldering is performed by heating. The solder ball 2ar is melted by heating and spreads on the pad 3a, and the height is about 0. Sticks at 23 mm.

Under ideal conditions, the gap G between the adjacent melted and fixed solders is maintained at about 0.15 mm, and sufficient insulation is secured.

As described with reference to FIGS. 12 and 13, when soldering under ideal conditions, in the case of a BGA type electronic component having a pitch of solder balls of 1.5 mm, the gap between solders is 0.3 mm.
In the BGA type electronic component having the same pitch of 1.0 mm, the pitch of the solder balls, that is, the density of the pads of the wiring pattern, becomes higher after fusion fixing so that the interval of 0.15 mm is formed between the solders. It becomes difficult to secure the space between the solders.

The above explanation is for the case where the ideal conditions are satisfied, but in reality, the accuracy of the mounting position of the electronic parts, the solder heating temperature, and the variation factors of the atmospheric conditions are added, and the result of the soldering is Changes.

FIG. 16 shows a solder ball pitch of 1.0 mm.
FIG. 3 is a cross-sectional view of a main part for explaining the structure of a soldering part when the BGA type electronic component of FIG.

FIG. 3A shows a state in which the mounting component 2a is soldered at a target value of the heating temperature at a position displaced by about 0.1 mm from the center of the pad 3a of the wiring pattern 3, and the wiring pattern 3 of the substrate 1 is shown. Of the resist film 1a on the outer peripheral surface of the pad 3a of
Has been applied.

Solder balls of the electronic component 2a to be mounted (deformed by heating to become 2ar ') flow out to the surface of the resist film 1a as shown by H and I due to mechanical vibration during heating and melting. There is. This solder flow-out causes a short circuit with an adjacent pad.

Further, FIG. 6B shows a state after soldering when the soldering temperature is high. If the heating temperature at the time of soldering is high, the fluidity of the melted solder is high, and thus it is easily affected by mechanical vibration.

Therefore, the melted solder causes a short circuit between the adjacent pads as shown in FIGS.

As described above, it is necessary to solder the BGA type electronic component to the substrate in consideration of the positional displacement when mounting the component, the surface tension of the melted solder, etc. , SOJ as well as BGA type
Type and SOP type electronic components are also mixed and mounted, it is difficult to satisfy the ideal condition for soldering of BGA type electronic components, and there is a problem that the cost increases. .

The first object of the present invention is to solve the above-mentioned problems of the prior art and to have high reliability and at low cost.
An object of the present invention is to provide a surface-mount multilayer board on which various surface-mount electronic components including shapes can be mounted by soldering.

A second object of the present invention is to provide a liquid crystal display device constructed by using the above-mentioned surface mount multilayer substrate.

[0049]

In order to achieve the first object, the first invention according to claim 1 is a surface on which a plurality of electronic components including a ball grid array type electronic component are mounted. The mounted multilayer board has a resist film on the outer peripheral surface of each soldering pad at least at the mounting position of the ball grid array type electronic component, and the thickness of the resist film is the ball grid array type electronic component. Is approximately equal to the gap between the back surface and the surface mounting substrate after mounting.

In order to achieve the above first object,
According to a second aspect of the present invention, a resist film is provided on the outer peripheral surface of each soldering pad at least at the mounting position of the ball grid array type electronic component, and the film thickness of the resist film is the ball. A feature is that the height of the ball grid made of solder formed on the back surface of the grid array type electronic component from the back surface is approximately halved.

Further, in order to achieve the above-mentioned first object, a third invention according to a third aspect is that at least a surface of a mounting position of the ball grid array type electronic component of the surface mounting multilayer substrate is provided. The ball grid array type electronic component has a recess for accommodating a ball grid made of solder formed on the back surface, and a wiring pattern pad for soldering the ball grid is formed on the bottom surface of the recess. Characterize.

In order to achieve the above-mentioned second object, the fourth invention according to claim 4 forms at least a color filter, a common transparent electrode and an alignment film on one transparent substrate, and the other transparent substrate. A liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of transparent substrates on which at least transparent electrodes for pixel selection and an alignment film are formed on a substrate, and pixels of the liquid crystal cell are provided on the periphery of the pair of transparent electrodes of the liquid crystal cell. A liquid crystal display device having at least a surface-mount multilayer substrate on which one or a plurality of electronic components for applying a driving signal for driving is mounted, wherein the surface-mount multilayer substrate has at least a ball grid array type electronic component mounted thereon. , The back surface and the surface after the ball grid array type electronic component is substantially mounted on the outer peripheral surface of each soldering pad at the mounting position of the ball grid array type electronic component. And having a resist film applied to a film thickness equal to the gap between the instrumentation substrate.

Further, in order to achieve the above-mentioned second object, a fifth invention according to claim 5 is the surface of at least the mounting position of the ball grid array type electronic component of the surface mounting multilayer. Has a recess for accommodating a ball grid made of solder formed on the back surface of the ball grid array type electronic component, and forming a wiring pattern pad for soldering the ball grid on the bottom surface of the recess. The space between the back surface of the ball grid array type electronic component and the pad is made substantially equal to the gap between the back surface and the pad after mounting the electronic component.

[0054]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the BGA type electronic component is to be soldered to the pad of the wiring pattern by effectively utilizing the surface tension when the solder balls forming the ball grid array are melted. Therefore, there are technical solutions such as (1) improving the mounting position accuracy of electronic components, (2) accurately controlling the heating temperature, and (3) suppressing mechanical vibration. Both have limitations, and the manufacturing cost is high.

FIG. 1 is an explanatory view of the pitch intervals of the solder balls forming the ball grid array of the BGA type electronic component and the selection standard of the minimum interval between the back surface and the substrate surface of the electronic component after soldering. The solder ball pitch p (mm) is plotted on the horizontal axis and the minimum distance d (mm) between the back surface of the electronic component and the substrate surface is plotted on the vertical axis, and the amount of solder (solder ball diameter) (mm 5) are different from each other.

As shown in the legend of the figure, the distance d from the front surface of the substrate to the back surface of the electronic component is based on the conventional standard, and the solder surface is broken due to thermal expansion due to contact between the back surface of the electronic component and the front surface of the substrate. About 0.2 after soldering to prevent
mm (average 0.25 mm) was used as a guide. However, in the case of BGA type electronic parts, it is 0.1 mm or less, which is one half or less of the conventional standard.

Therefore, according to the present invention, the film thickness of the insulating resist film applied to the mounting position of the BGA type electronic component mounted on the surface mounting multilayer substrate is determined by the distance between the rear surface of the electronic part ratio and the upper surface of the substrate. Is set to an appropriate value so as to prevent the flow of melted solder, and a concave portion is formed at the position of the solder ball, or the BGA of the surface mounting multilayer substrate.
A recess for accommodating the solder balls that form the ball grid array of the electronic component is formed on the mounting surface, and a wiring pattern pad is formed on the bottom surface of the recess. The gap with the bottom surface is a proper value for preventing the flow of melted solder, and avoids short circuit between pads and insulation failure.

As described above, the thickness of the resist film applied to the surface mounting multilayer substrate is optimized or the recess is formed in the surface mounting multilayer substrate according to the height and the diameter of the solder ball of the BGA type electronic component. By doing so, the electronic component can be mounted at an accurate position, and the melted solder ball can flow out to the adjacent pad to prevent insulation failure, short circuit, and the like.

[0059]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows a first surface mounting multilayer substrate according to the present invention.
It is explanatory drawing of an Example, (a) is a top view, (b) is a side view, (c) is AA 'partial sectional view of (a), (d) is BB of (a). 'It is a partial cross-sectional view.

In the figure, reference numeral 1 is a surface mount multilayer substrate, and 1
a and 1b are resist films, 1c is a positioning mark, 2 is a surface mount electronic component, 2a is a BGA type electronic component, and 2b is an SOP.
Shaped electronic parts, 2c are SOJ type electronic parts, 3 is a wiring pattern, and 3a is a pad.

SOP type electronic component 2 of surface mount multilayer substrate 1
b, the thickness of the portion where the SOJ type electronic component 2c is mounted is 0.
A 02 mm resist film 1a is applied. This SOP type electronic component 2b or SOJ type electronic component 2c is shown in FIG.
As described above, the lead pins are arranged on the side edges of the electronic component body, and the lead pins are soldered to the pads 3a of the wiring pattern 3 as shown in the sectional view of (c).

On the other hand, in the portion of the surface mount multilayer substrate 1 where the BGA type electronic component 2a is mounted, a resist film 1b is further applied on the resist film 1a in accordance with the diameter and pitch of the solder balls, and the total thickness of the resist film is increased. 0.05 ~ 0.20 mm
And the pad 3 at the position of the solder ball.
A concave portion reaching a is formed.

As described above, by increasing the thickness of the resist film on the mounting portion of the BGA diameter electronic component and forming the concave portion at the position of the solder ball, the solder is prevented from flowing out from the pad at the time of melting, and the adjacent pad is provided. Insulation failure, short circuit, etc. can be prevented.

FIG. 3 shows a second surface mounting multilayer substrate according to the present invention.
FIG. 6 is an enlarged cross-sectional view of a soldering portion of a BGA electronic component for explaining a more detailed configuration of the embodiment of FIG. 1, in which a solder ball has a diameter of 0.5 mm, a height from a back surface is 0.46 mm, and a pitch is 1.0 mm. The case where the BGA diameter electronic component of is mounted.

In the figure, the diameter of the wiring pattern 3 of the substrate 1 is 0.4 mm, the diameter of its pad 3a is 0.8 mm, the thickness of the pad 3a is 0.06 mm, and the thickness of the resist film 1b is 0.12 mm. With a concave diameter of 0.6 mm,
Even when the mounting position of the electronic component is shifted and soldering is performed, even if the solder ball 2ar is melted by heating, the melted solder remains in the recess and does not flow out to the adjacent pad.

FIG. 4 shows a second surface mounting multilayer substrate according to the present invention.
FIG. 6 is an enlarged cross-sectional view of the soldering portion of the BGA electronic component for explaining the detailed configuration of the embodiment of FIG. Same as 3.

In the figure, 0.10 from the surface of the substrate 1
Digging in to form a recess, 0.02 mm around the periphery.
The resist film 1a is applied.

From the surface of the resist film 1a to the wiring pattern 3
The distance from the pad 3a to the surface of the pad 3a was set to 0.12 mm, and as shown on the left side of FIG.

Even in this case, the molten solder 2ar 'stays in the recess due to the surface tension as shown on the right side of FIG.
It does not flow to the adjacent pad.

FIG. 5 shows a third example of the surface mount multilayer substrate according to the present invention.
FIG. 6 is an enlarged cross-sectional view of a soldering portion of a BGA electronic component for explaining the detailed configuration of the embodiment of FIG. 3, except that the side wall of the recess formed in the substrate 1 has a tapered surface and the thickness of the wiring pattern 3 and its pad 3a. The diameter and height of the solder ball 2ar are as shown in FIG.
Is the same as

Also in this figure, as in the case of FIG.
The A-type electronic component was displaced from the proper position and mounted and heated.

Even in this case, the molten solder 2ar 'remains in the recess due to the surface tension and does not flow out to the adjacent pad.

As described above, when the BGA type electronic component is soldered, it is possible to prevent the short circuit between the adjacent wiring patterns as in the prior art described above, and it is possible to avoid the cost increase.

By using this surface mount multilayer substrate,
High-performance liquid crystal surface devices and other electronic devices can be obtained.

Next, an active mask type liquid crystal display device will be described as an example of an electronic device on which the above-described surface-mounted multilayer substrate of the present invention is mounted.

The active matrix type liquid crystal display device is provided with a non-linear element (switching element) corresponding to each of a plurality of pixel electrodes arranged in a matrix. Since the liquid crystal in each pixel is theoretically always driven (duty ratio 1.0), the active method has better contrast than the so-called simple matrix method that employs the time-division driving method. Then it is becoming an indispensable technology. A typical switching element is a thin film transistor (TFT).

An active matrix type liquid crystal display device using thin film transistors is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-309921 and "1.
2.5-inch active matrix color LCD ", Nikkei Electronics, pages 193-210, 1986 12
Known on the 15th of March, published by Nikkei McGraw-Hill, Inc.

FIG. 6 is a development perspective view for explaining a structural example of a TFT type liquid crystal display module which constitutes a liquid crystal display device on which a printed circuit board using a solder printing mask according to the present invention is mounted.

In the figure, SHD is a metal shield case which is an upper frame, WD is a display window which defines the effective screen of the liquid crystal display module, PNL is a liquid crystal panel consisting of liquid crystal display elements, and SPC (1 to 4) are Spacer, FPC
1 is a gate side flexible substrate, FPC2 and FPC3 are drain side flexible substrates, LP is a fluorescent tube, GB is a rubber bush, BL is a backlight, LCT is an inverter connector, LPC is a lamp cable, GC1 and GC2.
Is a rubber cushion, MCA is a lower case, MO is an opening,
PRS / SPS / GLB / RFS is a prism sheet / diffusion plate / light guide plate / reflection sheet, and PCB is an interface circuit board, which is composed of the above-mentioned surface mount multilayer board according to the present invention.

Each of the above components is laminated between the metal shield case SHD and the lower case MCA and is sandwiched and fixed to form a liquid crystal display module.

Various printed circuit boards (a board including the above-mentioned surface-mounted multi-layer board, hereinafter also simply referred to as a board) are attached around the liquid crystal panel PNL to drive for image display. In particular, by using, as the substrate PCB forming the power supply unit / controller unit, the one described in each of the above-mentioned surface mount multilayer substrates, it is possible to obtain a liquid crystal display device of high quality and long life.

On the back surface of the liquid crystal panel PNL, various optical sheets such as a prism sheet PRS, a diffusion sheet SPS and a reflection sheet RFS are laminated on the light guide GLB.
Liquid crystal display panel PNL with illumination light from the backlight BL
The image formed on is illuminated and displayed on the display window WD.

FIG. 7 is a connection diagram of an equivalent circuit of the display matrix portion of the liquid crystal display module according to the present invention and its peripheral circuit. Although the figure is a circuit diagram, it is drawn corresponding to the actual geometrical arrangement.

In the figure, AR means a matrix array (TFT-LCD) in which a plurality of pixels are arranged two-dimensionally, X means a video signal line DL, and subscripts G, B and R are green, blue and red, respectively. Are added corresponding to the pixels. Further, Y means the scanning signal line GL, and the subscripts 1, 2, 3, ...
・, End are added according to the order of scanning timing.

The video signal lines X (subscripts omitted) are alternately connected to the upper (or odd) video signal drive circuit (upper drain driver) He and the lower (or even) video signal drive circuit (lower drain driver) Ho. ing.

The scanning signal line Y (subscript omitted) is connected to a vertical scanning circuit (gate driver) V.

The SUP supplies information for a CRT (cathode ray tube) from a power supply circuit or a host (upper processing unit) for obtaining a stabilized voltage source obtained by dividing a plurality of voltages from one voltage source to a TFT liquid crystal. A circuit that constitutes a power supply unit / controller unit including a circuit for exchanging information for a display device (see FIG. 6).
The interface circuit board PCB) shown in FIG.

In such a structure, the storage capacitor C
When the thin film transistor TFT switches, add acts to reduce the influence of the gate potential change ΔVg on the midpoint potential (pixel electrode potential) Vlc.

This can be expressed by the following equation.

ΔVlc = {Cgs / (Cgs + Cadd + Cpix)} × ΔVg where Cgs is the gate electrode G of the thin film transistor TFT.
Parasitic capacitance formed between T and source electrode SD1, C
pix is a capacitance formed between the transparent pixel electrode ITO1 (PIX) and the common transparent pixel electrode ITO2 (COM), ΔV
lc represents the amount of change in the pixel electrode potential due to ΔVg.

This variation ΔVlc causes a direct current component applied to the liquid crystal, and the value can be reduced as the holding capacitance Cadd is increased. Further, the storage capacitor element Cadd also has the function of prolonging the discharge time, and stores the image information for a long time after the thin film transistor TFT is turned off. The reduction of the direct current component applied to the liquid crystal can improve the life of the liquid crystal and can reduce so-called burn-in in which the previous image remains when the liquid crystal display screen is switched.

The storage capacitance of the storage capacitor Cadd is 4 to 8 times (4.times.) The liquid crystal capacitance Cpix due to the writing characteristics of the pixel.
Cpix <Cadd <8 · Cpix) and a value about 8 to 32 times (8 · Cgs <Cadd <32 · Cgs) with respect to the parasitic capacitance Cgs.

[0094] initial stage of the scanning signal lines GL, which is used only as a storage capacitor electrode line (Y _O) is at the same potential as the common transparent pixel electrode.

FIG. 8 is a perspective view of a notebook-type personal computer or word processor as an example of electronic equipment in which the liquid crystal display device according to the present invention is mounted. The MDL is a liquid crystal panel PNL, and circuit boards PCB1, PCB2, PCB3 and a back panel. The liquid crystal display module described with reference to FIG. 6 in which lights and the like are combined, and IV is an inverter power supply. The CPU is a central processing unit, and CT, TCON, and CR are electronic components such as various drive ICs mounted on the board.

In the figure, a liquid crystal panel P such as a driving IC is shown.
Multilayer flexible substrate PC as a peripheral circuit for COG mounting on the NL and peripheral drain and gate drivers
By adopting bending mounting for B1 and PCB2, the external size can be significantly reduced compared to the conventional case. Further, by adopting the above-mentioned surface-mounting multilayer board according to the present invention to the board (interface board) PCB3 on which the electronic parts of the power source section and the control section are mounted, the soldering trouble is eliminated, and the reliability and long life are improved. Electronic equipment can be obtained.

In this example, since the substrate PCB1 on which the drain driver peripheral circuit is mounted can be arranged only above the display portion above the hinge of the electronic device, the display area can be increased and compact mounting is possible. .

A signal from the host of the electronic device is first sent from the connector located at the substantially center of the interface board PCB3 on the left side of the figure to the display control integrated circuit element (TCO).
N), the display data converted here is P
It flows to the drain driver peripheral circuit mounted on the CB1.

As described above, by using the surface-mounting multilayer substrate and the multilayer flexible substrate, it is possible to eliminate the restriction on the lateral width of the electronic device and provide a small-sized information device with low power consumption.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention. is there.

Further, in the liquid crystal display device of the present invention, various electronic components mounted on the surface-mounting multilayer substrate are highly reliable, and at the same time, low cost and long life and high quality image display are possible. Needless to say, the present invention is applicable not only to the surface-mounting multilayer board but also to a single-layer surface-mounting board.

[0102]

As described above, the surface mounting multilayer substrate of the present invention is adjusted to the height of the ball grid array (solder balls) of the BGA type electronic component from the back surface of the electronic component and its diameter. By providing the resist film or the concave portion formed by digging the substrate at the pad position of the wiring pattern of the substrate, the BGA type electronic component to be mounted can be precisely positioned, and the solder flows out when the solder ball is heated. Suppressed and accurate soldering is performed by the synergistic effect with the surface tension of the melted solder, and the occurrence of short circuit and insulation failure are prevented.

By using this surface mount multilayer substrate, a high quality and long life liquid crystal display device can be constructed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of pitch intervals of solder balls forming a ball grid array of a BGA type electronic component and selection criteria of a minimum interval between a back surface and a substrate surface of the electronic component after soldering.

FIG. 2 is an explanatory diagram of a first embodiment of a surface-mount multilayer substrate according to the present invention.

FIG. 3 is an enlarged cross-sectional view of a soldering portion of a BGA electronic component for explaining a more detailed structure of the second embodiment of the surface mount multilayer substrate according to the present invention.

FIG. 4 is an enlarged cross-sectional view of a soldering portion of a BGA electronic component for explaining the detailed configuration of the second embodiment of the surface mount multilayer substrate according to the present invention.

FIG. 5 is an enlarged cross-sectional view of a soldering portion of a BGA electronic component for explaining the detailed configuration of the third embodiment of the surface mount multilayer substrate according to the present invention.

FIG. 6 is a developed perspective view illustrating a structural example of a TFT type liquid crystal display module that constitutes a liquid crystal display device on which a printed circuit board using a solder printing mask according to the present invention is mounted.

FIG. 7 shows a wiring diagram of an equivalent circuit of a display matrix section of a liquid crystal display module according to the present invention and a peripheral circuit thereof.

FIG. 8 is a perspective view of a notebook-type personal computer or word processor as an example of an electronic apparatus in which the liquid crystal display device according to the present invention is mounted.

FIG. 9 is a schematic diagram illustrating an example of a conventional surface mount multilayer substrate.

FIG. 10 is an explanatory diagram of a schematic configuration of various surface mount flat packages.

FIG. 11 is an explanatory diagram of an example of dimensions of a BGA type electronic component.

FIG. 12 is an explanatory diagram of a conventional soldering operation of a flat package type electronic component to a surface mounting multilayer substrate.

FIG. 13 is a sectional view of a soldering portion for explaining a mounting structure of an electronic component on a surface mounting multilayer substrate according to a conventional technique.

FIG. 14 is a cross-sectional view of a main part for explaining the structure of a soldering portion when a BGA type electronic component having a solder ball pitch of 1.5 mm is soldered under ideal conditions by applying an insulating resist film. is there.

FIG. 15 is a cross-sectional view of an essential part for explaining the structure of a soldering part when a BGA type electronic component having a solder ball pitch of 1.0 mm and an insulating resist film applied thereon is soldered under ideal conditions. is there.

FIG. 16 is a cross-sectional view of a principal part for explaining the structure of a soldering part when a BGA type electronic component having a solder ball pitch of 1.0 mm is soldered in a state where the mounting position is displaced and the soldering temperature is high.

[Explanation of symbols]

 1 surface mounting multilayer substrate 1a, 1b resist film 1c positioning mark 2 surface mounting electronic component 2a BGA type electronic component 2b SOP type electronic component 2c SOJ type electronic component 2ar solder ball (ball grid) 3 wiring pattern 3a pad.

Front page continued (72) Inventor Toshio Shiga 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd.

Claims (5)

[Claims] 1. A surface-mount multilayer substrate on which a plurality of electronic components including a ball grid array type electronic component are mounted, and at least outer peripheral surfaces of soldering pads at the mounting positions of the ball grid array type electronic component. A surface characterized by having a resist film on the surface thereof, and making the film thickness of the resist film approximately equal to the gap between the back surface and the surface mounting substrate after mounting the ball grid array type electronic component. Mounted multilayer board. 2. A surface mounting multilayer substrate having a plurality of electronic components including a ball grid array type electronic component mounted thereon, wherein at least the outer peripheral surface of each soldering pad at the mounting position of the ball grid array type electronic component. Has a resist film on the back surface, and the thickness of the resist film is approximately one half of the height from the back surface of the ball grid made of solder formed on the back surface of the ball grid array type electronic component. A surface-mount multilayer substrate characterized by: 3. A surface-mount multilayer substrate on which a plurality of electronic components including a ball-grid-array electronic component are mounted, wherein at least the surface of the surface-mount multilayer substrate on which the ball-grid-array electronic component is mounted is located. The ball grid array type electronic component has a concave portion for accommodating the ball grid made of solder formed on the back surface thereof, and a wiring pattern pad for soldering the ball grid is formed on the bottom surface of the concave portion. A surface mounting method in which the distance between the back surface of the ball grid array type electronic component and the pad is approximately equal to the gap between the rear surface and the surface mounting substrate after mounting the electronic component. Multilayer board. 4. A liquid crystal layer between a pair of transparent substrates in which at least a color filter, a common transparent electrode and an alignment film are formed on one transparent substrate and at least a pixel selection transparent electrode and an alignment film are formed on the other transparent substrate. A liquid crystal cell formed by sandwiching the liquid crystal cell, and a surface-mount multi-layered board on which one or a plurality of electronic components for applying drive signals for driving pixels of the liquid crystal cell are mounted on the periphery of the pair of transparent electrodes of the liquid crystal cell. In the liquid crystal display device having at least:
The array-type electronic component is mounted, and the back surface and the surface-mounting board after mounting the ball-grid array-type electronic component on the outer peripheral surface of each soldering pad at the mounting position of the ball-grid-array type electronic component. A liquid crystal display device characterized in that it has a resist film applied with a substantially equal film thickness in a gap between and. 5. A liquid crystal layer between a pair of transparent substrates in which at least a color filter, a common transparent electrode and an alignment film are formed on one transparent substrate, and a pixel selection transparent electrode and an alignment film are formed on the other transparent substrate. A liquid crystal cell formed by sandwiching the liquid crystal cell, and a surface-mount multi-layered board on which one or a plurality of electronic components for applying drive signals for driving pixels of the liquid crystal cell are mounted on the periphery of the pair of transparent electrodes of the liquid crystal cell. A liquid crystal display device having at least: a ball grid made of solder formed on the back surface of the ball grid array type electronic component at least on the surface of the surface mounting multilayer substrate where the ball grid array type electronic component is mounted. And a pad of a wiring pattern for soldering the ball grid is arranged on the bottom surface of the recess, ·grid·
A liquid crystal display device, wherein a distance between the back surface of the array-type electronic component and the pad is substantially equal to a distance between the back surface and the pad after mounting the electronic component.